A wide variety of improvements have been made in recent years in the eyewear field, particularly as it relates to eyewear for use in active sports. For example, the unitary cylindrical lens was popularized by the Blades.RTM. (Oakley, Inc.) eyewear which incorporated, among others, the technology of U.S. Pat. No. 4,859,048 to Jannard. Toroidal unitary lens geometry having a constant horizontal radius throughout was introduced through a variety of products in the M Frame.RTM. line of eyeglasses, also produced by Oakley, Inc. See, e.g., U.S. Pat. No. 4,867,550 to Jannard. Various other improvements in eyewear systems suited for use in active sports are exemplified in U.S. Pat. Nos. 4,674,851, 4,730,915, 4,824,233, 4,867,550, 5,054,903, 5,137,342, 5,208,614 and 5,249,001, all to Jannard, et al.
The foregoing designs as well as other active sports eyeglasses on the market generally utilize a unitary lens or dual lenses formed from a polymer such as polycarbonate, which is mounted in a polymeric frame. Alternatively, the prior art includes eyeglasses in which glass or polymeric lenses have been mounted in frames formed from thin metal sections such as metal wire.
One continuing objective in the field of high quality eyewear, particularly that intended for use in high speed action sports, is minimizing distortion introduced by the eyewear. Distortion may be introduced by any of a variety of influences, such as poor construction materials for the optical portion of the lens, and inferior polishing and/or molding techniques for the lens. In addition, optical distortion can result from the interaction of the lens with the frame, including flexing of the frame and lens, as well as movement of the plane lying on a tangent to the center point of one optical zone with respect to the plane lying on a tangent to the center point of the other optical zone.
The technology exists for satisfactorily minimizing distortion introduced by characteristics of the lens alone. However, the overall optical precision of active sports eyewear up to this point has been limited by the combination of the polymeric lens in a polymeric or flexible wire frame. Eyeglass systems thus formed are susceptible to bending and flexing due to a variety of environmental causes such as impact, storage induced and other external forces, forces resulting from the assembly process of the eyewear, and exposure to heat. Flexing of the lens or spatial deviation of one lens with respect to the other undesirably changes refractive properties of the eyeglasses, whether the lens is corrective (prescription) or non-corrective.
Thus, there remains a need for a dimensionally stable support structure for eyeglass lenses, suitable for use with corrective and non-corrective lenses in rugged, high durability eyewear. Preferably, the eyewear remains aerodynamically suited for active sports such as high speed bicycle racing, skiing and the like, and weighs no more than necessary to accomplish the foregoing objectives.